How Much Aspartame Is Dangerous?

Aspartame is used as an artificial sweetener because it is 200 times sweeter than sugar; meaning, only 1/200th the amount is needed to perceive the same degree of sweetness. The significance of this is the reduction of calorie intake, thus its use in diet foods. But aspartame is controversial because it is digestible by the body. That it breaks down into toxic chemicals raises the question: How much is safe?

Composition

• Aspartame is composed of two amino acids (phenylalanine and aspartic acid) and an alcohol (methanol). Aspartame is broken down into these three constituents in the body. The enzyme chymotrypsin separates the methanol from aspartame in the small intestine--you may know methanol as wood alcohol. The liver breaks down the methanol further, into formaldehyde, then into formic acid, on the way to breaking it down into water and carbon dioxide. Both formaldehyde and formic acid are toxic.

Formaldehyde

• Formaldehyde, which you might remember from dissecting frogs in biology class, is used as a preservative. Formaldehyde seeps into the tissues and forms crosslinks with proteins, preventing them from carrying out chemical reactions. Formaldehyde is therefore useful for such preservation as embalming, leather tanning and wood finishing. It is also a neurotoxin, interferes with DNA replication and probably causes cancer and birth defects.

Formic Acid

• The liver breaks down the formaldehyde into formic acid, which disrupts the function of the mitochondria, the powerhouses of cells. Optic nerves are particularly susceptible to mitochondrial shutdown, which is why methanol poisoning is associated with blindness.

EPA Dosage

• Aspartame is one-tenth methanol. A can of soda with 180mg of aspartame has about 20mg of methanol in it. According to the CDC website, the EPA recommends "that an adult should not drink water containing more than 1 milligram of formaldehyde per liter of water (1 mg/L) for a lifetime exposure, and a child should not drink water containing more than 10 mg/L for 1 day or 5 mg/L for 10 days." (Notice that this doesn't mean the adult in more susceptible, but instead determines a lifetime limit, which is important because these toxins accumulate.)

  If 5 percent of methanol in a can of soda is retained long enough to become formaldehyde (based on the retention rate found in mice in a University of Barcelona study), drinking one can of soda with aspartame exceeds one of these three limits. Remember that this is based on 20mg per can. (A can of soda is 355ml.) There are sodas that approach nearly twice this concentration.

  Dr. Woodrow Monte of Arizona State University wrote in the Journal of Applied Nutrition, "When diet sodas and soft drinks, sweetened with aspartame, are used to replace fluid loss during exercise and physical exertion in hot climates, the intake of methanol can exceed 250 mg/day or 32 times the Environmental Protection Agency's recommended limit of consumption for this cumulative poison."

Cancer

• The increase in cancer risk of formaldehyde above control levels does not appear until levels on the order of 50 to 100 cans per day, depending on the amount per can and weight of the individual, according to a 2005 study in Environmental Health Perspectives. Note that cancer is not the only effect of formaldehyde and also that soda is not the only source of aspartame.

An Independent Study

• A private citizen ran an aspartame study on rats in which two packets of aspartame was dissolved per 8 ounces of the experimental group's drinking water, not an unusual density that people use in coffee. The rats were allowed to drink however much they wanted, as is the case with many people. The comparison with the control group can be found at myaspartameexperiment.com. It also includes helpful references. Warning: the photos are graphic.

Further Research

• If you wish to explore the subject on your own but want to avoid biased information, either from corporate, political or conspiracy-theory interests, it is helpful to identify them. For example, many studies are funded by the food industry (e.g. NutraSweet and Monsanto). Also, the distinction between FDA position papers and internal memos of public record should be observed. Both these problems can be found at the Snopes article on aspartame. For example, for decades the American Council on Science and Health has been cited for its heavy funding by the chemical and pharmaceutical industry and bias, including a 2004 Tufts University report that encourages seeking information elsewhere. The CDC, EPA and NIH might be better sources. Also, research from outside the U.S. is available at PubMed. Less heat and more light can be found by searching on methanol or formaldehyde than searching on aspartame.